Multipath plate-and-shell heat exchanger

ABSTRACT

The present invention relates to a plate-and-shell heat exchanger ( 100 ) having a stack of plate pairs ( 50, 60 ) positioned in a shell ( 20 ), where the stack of plate pairs ( 50, 60 ) includes a plurality of plate pairs of a first type ( 50 ) and a plurality of plate pairs of a second type ( 60 ). Each plate pair ( 50, 60 ) has two heat transfer plates ( 10 ) being connected to each other and forming a cavity ( 11 ) there between, and forming an inlet opening ( 13   a,    13   b ) and an outlet opening ( 13′   a,    13′   b ). First inner flow paths ( 12   a ) are formed through the first inlet openings ( 13   a ), the cavities ( 11 ) of the plate pairs of the first type ( 50 ) and the first outlets ( 13′   a ). Second inner flow paths ( 12   b ) are formed through the second inlet openings ( 13   b ), the cavities ( 11 ) of the plate pairs of the second type ( 60 ) and the second outlets ( 13′   b ). A third outer flow path ( 22 ) is defined within the shell and between plate pairs of the first type ( 50 ) and plate pairs of the second type ( 60 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims foreign priority benefits under 35 U.S.C. § 119from Danish Patent Application No. PA202170625, filed Dec. 16, 2021, thecontent of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a plate-and-shell heat exchanger and aheat transfer plate for a plate-and-shell heat exchanger.

BACKGROUND

Plate-and-shell heat exchangers comprise a plurality of stackedstructured plates positioned within a shell or casing. The plates areconnected in pairs such that a first fluid flow path for a first fluidis provided at least partially within the connected pairs of plates. Thepairs of connected plates are designed to fluidly connect a first inletopening to a first outlet opening of the heat exchanger, thereby formingthe first fluid flow path. A second fluid flow path for a second fluidis provided outside of the connected pairs of plates and separated fromthe first fluid flow path by the plates. The second fluid flow pathfluidly connects a second inlet opening to a second outlet opening. Heatexchange takes place between fluid flowing in the first fluid flow pathand fluid flowing in the second fluid flow path.

The second fluid enters the shell of the heat exchanger through thesecond inlet opening, flows along the complex second fluid flow pathinside the shell and out through the second outlet opening. As thesecond fluid enters the shell of the heat exchanger it undergoes acomplex change from a tubular or cylindrical flow through, e.g., a pipeinto a branched flow past the various components of the inside of theheat exchanger.

Depending on the inside layout of the heat exchanger, the first andsecond fluid flows may be obstructed in some regions and/or guided in anon-uniform way, such that the heat transfer rate between the two fluidsinside the heat exchanger is reduced. Further, the pressures, such asthe pressures in the areas of the openings and in the centre flowsections of the plates, may be significant, and thus it is a goal tomake a better pressure distribution over the plates.

SUMMARY

The invention provides a plate-and-shell heat exchanger comprising astack of plate pairs positioned in a shell, where the stack of platepairs comprises a plurality of plate pairs of a first type and aplurality of plate pairs of a second type, wherein:

-   -   each plate pair of the first type comprises two heat transfer        plates being connected to each other and forming a cavity there        between, and comprising a first inlet opening and a first outlet        opening, and    -   each plate pair of the second type comprises two heat transfer        plates being connected to each other and forming a cavity there        between, and comprising a second inlet opening and a second        outlet opening,        wherein the first inlet openings and the first outlet openings        of the plate pairs of the first type are connected to each other        so as to form first inner flow paths through the first inlet        openings, the cavities of the plate pairs of the first type and        the first outlets,        wherein the second inlet openings and the second outlet openings        of the plate pairs of the second type are connected to each        other so as to form second inner flow paths through the second        inlet openings, the cavities of the plate pairs of the second        type and the second outlets,        and wherein a third outer flow path is defined within the shell        and between plate pairs of the first type and plate pairs of the        second type.

Thus, the invention provides a plate-and-shell heat exchanger, i.e. aheat exchanger of the kind which comprises a stack of plates arrangedwithin a shell. In the heat exchanger according to the invention theplates forming the stack of plates are in the form of plate pairs, eachplate pair comprising two heat transfer plates being connected to eachother in such a manner that a cavity is formed between the heat transferplates.

The stack of plate pairs comprises a plurality of plate pairs of a firsttype and a plurality of plate pairs of a second type. Each plate pair ofthe first type comprises a first inlet opening and a second inletopening. Similarly, each plate pair of the second type comprises asecond inlet opening and a second outlet opening.

The first inlet openings and the first outlet openings of the platepairs of the first type are connected to each other so as to form firstinner flow paths through the first inlet openings, the cavities of theplate pairs of the first type and the first outlets. Accordingly, aplurality of parallel first inner flow paths is formed, through thecavities of the plate pairs of the first type. Since the respectivefirst inlets and first outlets are connected to each other, theseparallel first flow paths can be connected to the same fluid source, andthereby the same kind of fluid will flow through all of the first innerflow paths during operation of the heat exchanger. In the following thisfluid will be denoted the first fluid.

Similarly, the second inlet openings and the second outlet openings ofthe plate pairs of the second type are connected to each other so as toform second inner flow paths through the second inlet openings, thecavities of the plate pairs of the second type and the second outlets.Thereby a plurality of parallel second inner flow paths are formed,similarly to the first inner flow paths described above. The remarks setforth above are, accordingly, equally applicable here. The fluid flowingthrough the parallel second inner flow paths is, in the following,denoted the second fluid.

Thus, two separate fluids, i.e. the first fluid and the second fluid,are supplied to the first inner flow paths and to the second inner flowpaths, respectively, independently of each other.

Furthermore, a third outer flow path is defined within the shell andbetween the plate pairs of the first type and plate pairs of the secondtype. In the following, the fluid flowing in the third outer flow pathis denoted the third fluid.

Thus, during operation of the heat exchanger, heat exchange takes placebetween, on the one hand, the third fluid and, on the other hand, eachof the first fluid and the second fluid. In other words, the third fluidexchanges heat with the first fluid as well as with the second fluid.This provides a compact design of the heat exchanger, while ensuring asuitable temperature of the first fluid as well as of the second fluid,in an easy and efficient manner, and while preventing mixing among thethree kinds of fluid.

Accordingly, a first fluid flowing in the first inner flow paths as wellas a second fluid flowing in the second inner flow paths may exchangeheat with a third fluid flowing in the third outer flow path.

Each plate pair of the first type may further be provided with a secondinlet opening and a second outlet opening, and the second inlet openingand the second outlet opening of a given plate pair of the first typemay be sealed from the first inlet opening, the first outlet opening andthe cavity defined by the given plate pair of the first type.

According to this embodiment, the first inner flow paths and the secondinner flow paths are efficiently separated from each other, therebypreventing mixing of the first fluid and the second fluid. However,since the second inlet openings and the second outlet openings areformed in the plate pairs of the first type, the plate pairs of thefirst type and the plate pairs of the second type may in fact bedesigned identically or in a similar manner, the only difference beingthat in the plate pairs of the first type the cavities are connected tothe first inlet openings and the first outlet openings, whereas in theplate pairs of the second type the cavities are connected to the secondinlet openings and the second outlet openings. This reduces themanufacturing costs of the heat exchanger.

Similarly, each plate pair of the second type may further be providedwith a first inlet opening and a first outlet opening, and the firstinlet opening and the first outlet opening of a given plate pair of thesecond type may be sealed from the second inlet opening, the secondoutlet opening and the cavity defined by the given plate pair of thesecond type. The remarks set forth above with reference to the platepairs of the first type are equally applicable here.

The first inlet opening and the first outlet opening may be formed inone of the heat transfer plates of the plate pair, and the second inletopening and the second outlet opening may be formed in the other of theheat transfer plates of the plate pair.

According to this embodiment, it is efficiently ensured that the firstinlet/outlet openings and the second inlet/outlet openings do not comeinto contact with each other, thereby efficiently preventing mixing ofthe first fluid and the second fluid, also at or near the inlet openingsand the outlet openings.

The plate pairs of the first type and the plate pairs of the second typemay be identical, and rotated at an angle relative to each other arounda centre axis of the plate pairs. According to this embodiment, anidentical design is applied for the plate pairs of the first type andthe plate pairs of the second type, respectively, and the orientation ofthe plate pairs determine whether a given plate pair is regarded as aplate pair of the first type or as a plate pair of the second type. Thecentre axis of the plate pairs may be an axis of symmetry of the platepair.

The plate pairs of the first type and the plate pairs of the second typemay be arranged alternatingly in the stack of plate pairs. According tothis embodiment, the plate pairs are arranged in the stack of platepairs in such a manner that each plate pair of the first type isarranged between two plate pairs of the second type, or between a platepair of the second type and an end plate, and each plate pair of thesecond type is arranged between two plate pairs of the first type, orbetween a plate pair of the first type and an end plate. Thereby thefirst inner flow paths and the second inner flow paths are also arrangedalternatingly in the heat exchanger. This provides even and appropriateheat exchange with each of the first and second fluids, simultaneously.

The heat transfer plates forming the plate pairs of the first typeand/or the heat transfer plates forming the plate pairs of the secondtype may be identical, and rotated 180° around a centre axis of theplate pairs.

According to this embodiment, identical heat transfer plates are appliedfor forming the plate pairs of the first type and/or the plate pairs ofthe second type. The heat transfer plates may be regarded as defining afirst side and a second, opposite, side. When connecting the heattransfer plates in order to form a plate pair, the heat transfer platesare oriented relative to each other in such a manner that the firstsides of the heat transfer plates face each other, and the second sidesof the heat transfer plates form outer surfaces of the plate pair.Accordingly, the first sides of the heat transfer plates face the cavityformed between the heat transfer plates, and the second sides faceneighbouring plate pairs.

The plate pairs may have an outer shape which is circular, oval,pentangular or hexagonal. This allows the stack of plate pairs to definea shape which matches a shape of the shell which accommodates the stackof plate pairs.

The first inlet openings and the first outlet openings of the platepairs of the first type may be connected by connection elements, and thesecond inlet openings and the second outlet openings of the plate pairsof the second type may be connected by connection elements. Thisefficiently keeps the respective flow paths separated and preventsunintentional mixing of the various fluids.

The plate pairs of the first type and the plate pairs of the second typemay be sealingly connected to each other at outer rims of the inletopenings and the outlet openings. This efficiently preventsunintentional mixing of the first fluid and the second fluid at theregions near the inlet openings and the outlet openings.

The plate-and-shell heat exchanger may be connected to an electrolyzersuch that a fluid feed to a cathode of the electrolyzer, a fluid feed toan anode of the electrolyzer, as well as a common heating or coolingfluid passes through the plate-and-shell heat exchanger.

According to this embodiment, the fluid fed to the cathode of theelectrolyzer as well as the fluid fed to the anode of the electrolyzeris heated or cooled simultaneously be a heating or cooling fluid flowingin the third outer flow path. Thereby it is ensured that both of thefluids supplied to the electrolyzer have an appropriate temperature, andthis is ensured in an easy and efficient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a prior art plate-and-shell kind heatexchanger;

FIGS. 2A and 2B illustrate a prior art heat transfer plate and an edgeview of connected pairs of connected plates of a plate-and-shell kindheat exchanger;

FIG. 3 illustrates a prior art plate-and-shell kind heat exchangershowing flow distributions at the two sides of a heat transfer plate;

FIG. 4 illustrates a heat transfer plate according to an embodiment ofthe present invention;

FIGS. 5A and 5B illustrate a heat transfer plate and an edge view ofconnected pairs of connected plates of a plate-and-shell kind heatexchanger according to an embodiment of the present invention, showing aset of inlet openings and outlet openings, where a first inlet openingand a first outlet opening are open, while a second inlet opening and asecond outlet opening are closed;

FIGS. 6A and 6B illustrate a heat transfer plate similar to the heattransfer plate of FIGS. 5A and 5B, but where a second inlet opening anda second outlet opening are closed, while a first inlet opening and asecond inlet opening are closed;

FIG. 7 illustrates an embodiment of the present invention with firstkind pair of heat transfer plates and second kind pair of heat transferplates being formed with non-overlapping sections;

FIG. 8 is a sideview of a non-overlapping section showing a connectionelement positioned in relation to an opening;

FIG. 9 is a top-view of the first kind pair of heat transfer plates andsecond kind pair of heat transfer plates being positioned on top of eachother, and being formed with non-overlapping sections;

FIG. 10 is a sideview of non-overlapping sections of first kind heattransfer plates reaching over the edge of second kind heat transferplates with their openings connected by connection elements;

FIG. 11 illustrates an alternative embodiment of first kind pair of heattransfer plates and second kind pair of heat transfer plates formed withnon-overlapping sections; and

FIG. 12 illustrates a plate-and-shell heat exchanger according to anembodiment of the present invention used in relation to an electrolyzer.

DETAILED DESCRIPTION

The detailed description and specific examples indicating embodiments ofthe invention are given by way of illustration of the basic concept onthe invention only.

FIGS. 1A, 1B, 2A, 2B and 3 illustrate an embodiment heat exchanger as itis known from the prior art.

FIG. 1A shows an exploded view of a plate-and-shell heat exchanger 100.The heat exchanger 100 comprises a shell 20 and a plurality of sealedpairs of heat transfer plates 10 within the shell 20.

The shell 20 may be of a hollow cylindrical shape and the plates 10 maybe of a corresponding shape and size such that they can be fit into theshell 20. Other shapes of the shell 20 and plates 10 are also possible,however shapes are preferred, which allow for a substantially closepositioning of the plates 10 within the shell 20.

The plates 10 in the pairs are in the heat transfer sections 32contacting each other by patterns 30, possible intersecting. This formsfluidly connected first cavities 11 for providing an inner fluid flowpath 12 for a first fluid flow indicated by the corresponding arrows.The first fluid flow enters and leaves the heat exchanger 100 through afirst inlet opening 23 and a first outlet opening 23′. The firstcavities 11 are surrounded by two adjacent plates 10, which areconnected to each other, as is shown more clearly in FIG. 1B and as willbe described below in more detail below. FIG. 1B shows the heatexchanger 100 in a sectional view and in an assembled state.

The plates 10 in the pairs may be connected, e.g. by welding or brazing,at their plate rims, or outer edges, 14 a, possibly also at theconnected intersecting patterns 30. Two and two this forms firstcavities 11 for a sealed inner fluid flow path 12 from a first inletopening 23 to a first outlet opening 23′.

The plates 10 comprise plate openings 13, 13′ for connecting fluidlyadjacent plates 10 to each other and to the first inlet and outletopening 23, 23′. The two adjacent plates 10 of two connected pairs maybe connected and sealed together by, e.g., a welding or brazing alongthe opening rim, or opening edge, 14 b of the plate openings 13, 13′.

An outer fluid flow path 22 is formed at the outside surfaces of theplates 10 by the connected patterns 30 projecting outwardly relative tothe first cavities 11 of the connected pairs of plates 10, thus at theopposite side of the plates 10. The outer fluid flow path 22, thus, isformed outside of the sealed pairs of plates 10 and inside of the shell20 and is connected to a second inlet opening 24 and second outletopening 24′. A second fluid flow enters and leaves the heat exchanger100 through second inlet opening 24 and the second outlet opening 24′,respectively.

The shell 20 forms a second cavity 21 in which the plates 10 arearranged and in which an outer fluid flow path 22 for a second fluidflow is provided. The second fluid flow enters and leaves the heatexchanger 100 through second inlet opening 24 and the second outletopening 24′, respectively.

The inner flow path 12 and the outer fluid flow path 22 are separatedand sealed from each other, respectively, by the plate pairs beingconnected at the plate rims 14 a and by the plate pairs being connectedat their opening rims 14 b of the openings 13, 13′. The heat exchangeoccurs between the two fluids flowing separated from each other, and viathe plates 10.

Fluid for the inner flow path 12 is sealed from the inside of the secondcavity 21 inside the shell 20, and therefore from the outer flow paths22, but each cavity 11 is fluidically contacted with the other cavities11 of the connected plate 10 pairs in the stack by the openings 13, 13′,and thereby also with the first inlet 23 and the first outlet 23′.

Fluid for the outer flow path 22 is in fluid contact to the secondcavity 21, and thereby to the second inlet 24 and the second outlet 24′,over the rims 14 a of the plates 10, but is sealed from the cavities 11,as the two plates 10 in each pair are connected at their rims 14 a, andpairs are connected to neighbouring pairs at the (outer) rims 14 b ofthe openings 13, 13′.

FIG. 2A shows a detailed view of a heat transfer plate 10 of a prior artplate-and-shell heat exchanger 100. The plate 10 sheet is possibly madeof metal.

The pattern 30 at the heat transfer sections 32 is seen as beingcorrugated having a series of parallel ridges and grooves. It may beformed by pressing the corrugations into a flat sheet preform. Theplates 10 then are connected such that every second plate is turned, orformed, with the corrugated patterns 30 of neighbouring plates crossingeach other rather than extending in parallel. The crossing points thenform the contacts of the plates 10 in the heat transfer sections 32.

FIG. 2B shows a detailed sectional view of a plurality of connected heattransfer plates 10. Two adjacent plates 10 are connected at their outercircumferences, or at the rims 14 a of their outer edges. Thus, sealedpairs of connected plates 10 are provided for allowing the first fluidto flow through the inner fluid flow path 12, bounded by the connectedpairs of plates 10.

The outer fluid flow path 22 is guided between two adjacent pairs ofconnected plates 10 and separated from the inner fluid flow path 12 bythe plates 10. It comprises flat, narrow channels between closelypositioned plates 10. For efficient heat exchange, the second fluid flowrate in the vertical direction and between the pairs of connected plates10 as shown in FIG. 2B is essential. This flow component corresponds inapproximation to a radial or tangential component of the second fluidflow with respect to the shell 20.

FIG. 3 is a schematic view of parts of the inner fluid flow path 12 andthe outer fluid flow path 22 through the heat exchanger 100, along theheat transfer sections 32. The arrows at the one plate 10 indicate theinner fluid flow path 12 inside a pair of connected plates 10. The innerfluid flow path 12 enters the pair of connected plates 10 through one ofthe two plate openings 13 and leaves the pair of connected plates 10through the other of the two plate openings 13′.

The second plate shows a part of the outer fluid flow path 22 in a crosssection of the heat exchanger 100. This time, it is not the inside of apair of connected plates 10 which is shown, but the space between twosuch connected pairs of plates 10. The second fluid flow path 22 fillsthe second cavity 21. The second cavity 21 is bounded by the inside ofthe shell 20, the outsides of the pairs of connected plates 10, one ofwhich is shown in FIG. 3B, and possibly further structures containedwithin the shell 20. The outer flow path 22 enters the shell 20 throughthe second inlet opening 24 and leaves the shell 20 through the secondoutlet opening 24′. The second inlet opening 24 and the second outletopening 24′ may be positioned on opposite sides of the shell surface.

Since an inner fluid flow path 12 for a first fluid is formed at the oneside of a plate 10, and an outer fluid flow path 22 for a second fluidat the opposite side, the heat transfer between the first fluid insidethe first cavity 11 and the second fluid outside the first cavity 11 ishence facilitated over the plate 10. In the present context ‘inner’ and‘outer’ fluid flow paths 12, 22 refers to the first cavities 11 formedby the connected pairs of plates 10, and thus is related to the specificillustrated embodiment. In more general terms, there are two flow pathssealed from each other, one for the first fluid and one for the secondfluid.

To ensure a high efficiency of the heat exchanger 100, the fluidspreferably should distribute sufficiently over the entire width of theplates 10.

FIG. 4 illustrates a top view of a heat transfer plate 10 according toan embodiment of the present invention.

The plate 10 differs from the prior art plate 10 of FIG. 2A in that itincludes respectively a first inlet plate opening 13 a, a second inletplate opening 13 b, a first outlet plate opening 13′a, and a secondoutlet plate opening 13′b.

In the illustration, the respective first and second inlet and outletplate openings 13 a, 13 b, 13′a, 13′b are positioned at the samepositions as the plate openings 13, 13′ of FIG. 2A, but they could bepositioned at any suitable positions and have any suitable sizes, evenbeing differently sized.

The plate 10 is illustrated as being essentially circular, but couldhave any suitable form like oval, squared, rectangular, pentagonal,hexagonal, etc.

The respective first and second inlet and outlet plate openings 13 a, 13b, 13′a, 13′b are adapted to be sealed 35 in pairs, such that for oneinner fluid flow path 12 the second inlet opening 13 b and the secondoutlet opening 13′b are sealed 35 from the respective inner flow path12, and for another inner fluid flow path 12 the first inlet opening 13a and the first outlet opening 13′a are sealed 35 from the respectiveinner flow path 12.

The first inlet opening 13 a and the first outlet opening 13′a are incontact with other first inlet openings 13 a and first outlet openings13′a, and the second inlet opening 13 b and the second outlet opening13′b are in contact with other second inlet openings 13 b and secondoutlet openings 13′b. The first inlet opening 13 a and the first outletopening 13′a are sealed from the second inlet opening 13 b and thesecond outlet opening 13′b.

This forms a first inner flow path 12 a and a second inner flow path 12b, the first inner flow path 12 a being in fluid connection to the firstinlet opening 13 a and the first outlet opening 13′a, and the secondinner flow path 12 b being in fluid connection to the second inletopening 13 b and the second outlet opening 13′b.

The sealing 35 may be of any suitable kind. In one embodiment, a sealingelement 35, e.g. a rubber gasket, is positioned around the plateopenings 13 a, 13 b, 13′a, 13′b to be sealed, or a metal sealing 35 maybe included, possibly welded, brazed or fixed in another manner to theplates 10, e.g. at the opening rims 14 b. In one embodiment, the openingrims 14 b form flanges 35 to be connected to flanges of the neighbouringplate 10 of a pair, thus forming a sealing 35.

FIG. 5A illustrates a first pair type 50 of heat transfer plate 10,where the second inlet opening 13 b and the second outlet opening 13′bare sealed 35 from the respective first inner flow path 12 a, allowing afirst fluid entering the first inlet opening 13 a to leave via the firstoutlet opening 13′a without being mixed with a second fluid flowing viathe second inlet opening 13 b and the second outlet opening 13′b.

This is also illustrated in FIG. 5B, showing several connected plates 10forming the first cavities 11, the first inner flow paths 12 a and thesecond inner flows path 12 b, and showing the first inlet openings 13 a.The first fluid in the first inlet openings 13 a (represented by thewhite arrows) is seen entering only the first inner flow paths 12 a, butnot the second inner flow paths 12 b.

FIGS. 6A and 6B are similar to FIGS. 5A and 5B, with the difference thatthe first inlet opening 13 a and the first outlet opening 13′a aresealed 35 from the second inner flow path 12 b, allowing a second fluidentering the second inlet opening 13 b to leave via the second outletopening 13′b without being mixed with a first fluid flowing via thefirst inlet opening 13 a and the first outlet opening 13′a. Thisprovides a second pair type 60 of heat exchanger plates 10.

Similarly to FIG. 5B, FIG. 6B shows several connected plates 10 formingthe inner cavities 11, the first inner flow path 12 a and the secondinner flow path 12 b, but showing the second inlet openings 13 b. Thesecond fluid in the second inlet openings 13 b (represented by the whitearrows) is seen entering only the second inner flow paths 12 b, but notthe first inner flow paths 12 a.

The third fluid (represented by black arrows in FIG. 5B as well as inFIG. 6B) enters the outer flow paths 22 formed in the spaces between thetwo connected pairs of plates 10, and is distributed by the inner cavityof the shell 20, forming part of the outer flow path 22. Usually, theplates 10 will not extend to the inner surface of the shell 20, at leastnot in the region close to the first inlet opening 23, thus forming achamber for distribution of the third fluid.

The third fluid then is shared for the first and second fluids, flowingrespectively in the first inner flow path 12 a and the second inner flowpath 12 b. The third fluid could be a heating or cooling fluid to heator cool the first and second fluids, and could also be referred to as acommon heat exchanging fluid for the fluids in the first inner flow path12 a and the second inner flow path 12 b.

In the illustrations of FIGS. 5B and 6B, the first inner flow path 12 aand the second inner flow path 12 b of respectively the first 50 andsecond 60 pair types are seen positioned in succession of each other,such that every second of the first cavities 11 forms a first inner flowpath 12 a and every second forms a second inner flow path 12 b. In otherembodiments ‘bundles’ of first pair types 50 and second pair types 60may be positioned in succession of each other, e.g. 2 or 3 or 4 or morefirst pair types 50 and correspondingly 2 or 3 or 4 or more second pairtypes 60, possible then followed by 2 or 3 or 4 or more plates of thefirst pair types 50 etc.

In some embodiments the number of first pair types 50 may differ fromthe number of second pair types 60. This could, e.g., be the bundles ofpair types 50, 60 differing from each other.

The first pair type 50 and second pair type 60 could be identical, theone simply being rotated relative to and/or oriented differently fromthe other.

The presented embodiment has the advantage that the shape of the plates10 can be maintained and the heat transferring efficiency can beoptimised.

FIG. 7 shows an alternative embodiment of first 50 and second 60 pairtypes. The first pair type 50 is formed with one first inlet opening 13a and one first outlet opening 13′a, and the second pair type 60 isformed with one second inlet opening 13 b and one second outlet opening13′b. The first 50 and second 60 pair types could be identical, the onesimply being rotated and/or oriented differently.

The openings 13 a, 13′a, 13 b, 13′b of the first 50 and second 60 pairtypes in the illustrated embodiment are each positioned withinnon-overlapping sections 40 reaching out of the main part of the heattransfer plates 10, or the main part of the heat transfer sections 32.

FIG. 8 is a side view of a two such non-overlapping sections 40connected into a first 50 or second 60 pair type. Connection elements 45are positioned in contact with the plate openings 13 a, 13′a, 13 b,13′b.

FIG. 9 illustrates a first 50 and second 60 pair type positioned on topof each other, such that their non-overlapping sections 40 withrespective plate openings 13 a, 13′a, 13 b, 13′b are not covered by theother of the pairs.

FIG. 10 is a side view of a section of first 50 and second 60 pair typesstacked with the non-overlapping sections 40 of the one pair type 50, 60reaching outside the other pair type 60, 50. The respective plateopenings 13 a, 13′a, 13 b, 13′b are connected by connection elements 45positioned between the non-overlapping sections 40.

This embodiment efficiently enables a first fluid in the first pair type50 to be distributed to the following first pair types 50 without beingmixed with the second fluid in the second pair types 60, andcorrespondingly for the second pair types 60.

The embodiment of FIGS. 7 and 9 could be formed such that, when combinedas illustrated in FIG. 9 , the overall shape fits into a standard shell20, e.g. having a combined circular shape (or oval, squared, pentagonal,hexagonal, etc.).

FIG. 11 shows an alternative embodiment where the non-overlappingsections 40 are positioned like ‘ears’ or extensions to an otherwisestandard shaped heat transfer plate 10. Again, the first 50 and second60 pair types could be identical, the one simply being rotatedrelatively to the other, e.g. positioned in a mirrored orientationrelative to their non-overlapping sections 40, to allow positioning ofthe connection elements 45.

One example embodiment where the heat exchanger 100 according to thepresent invention with advantage could be used, is in electrolyzers 200,such as devices that use electricity to drive an electrochemicalreaction in order to produce hydrogen and oxygen from, e.g., water.

Such electrolyzers 200 are for example used within ‘Power-to-X’ whichrelates to electricity conversion, energy storage, and reconversionpathways that use surplus electric power, typically during periods wherefluctuating renewable energy generation exceeds load.

The hydrogen produced from an electrolyzer 200 is perfect for use withhydrogen fuel cells. The reactions that take place in an electrolyzerare very similar to the reactions taking place in fuel cells, except thereactions that occur in the anode and cathode are reversed. In a fuelcell, the anode is where hydrogen gas is consumed, and in anelectrolyzer 200, the hydrogen gas is produced at the cathode. A verysustainable system can be formed when the electrical energy needed forthe electrolysis reaction comes from renewable energy sources, such aswind or solar energy systems.

Direct current electrolysis (efficiency 80-85% at best) can be used toproduce hydrogen which can, in turn, be converted to, e.g., methane(CH₄) via methanation, or converting the hydrogen, along with CO₂ tomethanol, or to other substances.

The energy, such as hydrogen, generated in this manner, e.g. by windturbines, can thereby be stored for later usage.

Electrolyzers 200 can be configured in a variety of different ways andare generally divided into two main designs: unipolar and bipolar. Theunipolar design typically uses liquid electrolyte (alkaline liquids),and the bipolar design uses a solid polymer electrolyte (proton exchangemembranes).

Alkaline water electrolysis has two electrodes operating in a liquidalkaline electrolyte solution of potassium hydroxide (KOH) or sodiumhydroxide (NaOH). These electrodes are separated by a diaphragm,separating the product gases and transporting the hydroxide ions (OH⁻)from one electrode to the other.

Other fuels and fuel cells include phosphoric acid fuel cells, moltencarbonate fuel cells, solid oxide fuel cells and all their subcategoriesas well. Such fuel cells are adaptable for use as an electrolyzer aswell.

It is an advantage if the fluid solutions operating in the plant arewithin given temperatures to optimize the efficiency. It is also anadvantage if the plant could be compact and scalable.

The principle of using the present invention in such an electrolyzer200—or fuel cell, is illustrated in FIG. 12 , showing a plant 200, suchas an electrolyzer or fuel cell, equipped with a heat exchanger 100according to the present invention. In general, in the followingexample, the plant 200 is referred to as an electrolyzer 200, such as analkaline electrolyzer for producing hydrogen, but the term‘electrolyzer’ 200 refers in common to electrolyzers for producingfuels, or fuel cells using such fuels.

The embodiment shows an electrolyzer 200 comprising an electrolyzingdevice 202 formed of an assembly of diaphragms, etc. Regulating elements203 may be connected with the electronics, etc., such as to form thecontrol and regulation of operation of the electrolyzer 200.

The right-hand side of FIG. 12 shows an embodiment of the presentinvention, where the electrolyzer 200 is seen from the side andillustrating a heat exchanger 100 connected at its one end. The fluidsolutions circulating in the electrolyzing device 202 pass the heatexchanger 100 in order to regulate their temperatures. The first innerflow path 12 a of the heat exchanger 100 then would convey one of thefluids for the electrolyzer 100, and the second inner flow path 12 bwould convey the second of the fluids for the electrolyzer 100. Theouter fluid flow path 22 then would convey a heating or cooling medium.

The fluid solutions circulating in the electrolyzing device 200 thuspass the heat exchanger 100 in order to regulate their temperatures.

The left part of FIG. 12 shows the electrolyzer 200 seen from the front,where the electrolyzing device 202 appears circular, though it naturallycould have other shapes, such as oblate, oval, squared, polygonal, etc.The heat exchanger 100, and possibly the heat transfer plates 10, couldhave a corresponding shape, thus this could be related to make theelectrolyzing device 202 and heat exchanger 100 appearing as a singleunit, and the functioning of the heat exchanger 100.

The heat exchanger 100 may be connected to provide the desired operatingtemperature.

In the illustrated embodiment the heat exchanger 100 is connected to theelectrolyzing device 202 by squeezing them between flanges 300 heldtogether by rods 310. Alternatively, they could be connected by screws,brazed together, etc.

While the present disclosure has been illustrated and described withrespect to a particular embodiment thereof, it should be appreciated bythose of ordinary skill in the art that various modifications to thisdisclosure may be made without departing from the spirit and scope ofthe present disclosure.

1. A plate-and-shell heat exchanger comprising a stack of plate pairspositioned in a shell, where the stack of plate pairs comprises aplurality of plate pairs of a first type and a plurality of plate pairsof a second type, wherein: each plate pair of the first type comprisestwo heat transfer plates being connected to each other and forming acavity there between, and comprising a first inlet opening and a firstoutlet opening, and each plate pair of the second type comprises twoheat transfer plates being connected to each other and forming a cavitythere between, and comprising a second inlet opening and a second outletopening, wherein the first inlet openings and the first outlet openingsof the plate pairs of the first type are connected to each other so asto form first inner flow paths through the first inlet openings, thecavities of the plate pairs of the first type and the first outlets,wherein the second inlet openings and the second outlet openings of theplate pairs of the second type are connected to each other so as to formsecond inner flow paths through the second inlet openings, the cavitiesof the plate pairs of the second type and the second outlets, andwherein a third outer flow path is defined within the shell and betweenplate pairs of the first type and plate pairs of the second type.
 2. Theplate-and-shell heat exchanger according to claim 1, wherein a firstfluid flowing in the first inner flow paths as well as a second fluidflowing in the second inner flow paths exchange heat with a third fluidflowing in the third outer flow path.
 3. The plate-and-shell heatexchanger according to claim 1, wherein each plate pair of the firsttype is further provided with a second inlet opening and a second outletopening, and wherein the second inlet opening and the second outletopening of a given plate pair of the first type are sealed from thefirst inlet opening, the first outlet opening and the cavity defined bythe given plate pair of the first type.
 4. The plate-and-shell heatexchanger according to claim 1, wherein each plate pair of the secondtype is further provided with a first inlet opening and a first outletopening, and wherein the first inlet opening and the first outletopening of a given plate pair of the second type are sealed from thesecond inlet opening, the second outlet opening and the cavity definedby the given plate pair of the second type.
 5. The plate-and-shell heatexchanger according to claim 3, wherein the first inlet opening and thefirst outlet opening are formed in one of the heat transfer plates ofthe plate pair, and the second inlet opening and the second outletopening are formed in the other of the heat transfer plates of the platepair.
 6. The plate-and-shell heat exchanger according to claim 1,wherein the plate pairs of the first type and the plate pairs of thesecond type are identical, and rotated at an angle relative to eachother around a centre axis of the plate pairs.
 7. The plate-and-shellheat exchanger according to claim 1, wherein the plate pairs of thefirst type and the plate pairs of the second type are arrangedalternatingly in the stack of plate pairs.
 8. The plate-and-shell heatexchanger according to claim 1, wherein the heat transfer plates formingthe plate pairs of the first type and/or the heat transfer platesforming the plate pairs of the second type are identical, and rotated180° around a centre axis of the plate pairs.
 9. The plate-and-shellheat exchanger according to claim 1, wherein the plate pairs have anouter shape which is circular, oval, pentangular or hexagonal.
 10. Theplate-and-shell heat exchanger according to claim 1, wherein the firstinlet openings and the first outlet openings of the plate pairs of thefirst type are connected by connection elements, and the second inletopenings and the second outlet openings of the plate pairs of the secondtype are connected by connection elements.
 11. The plate-and-shell heatexchanger according to claim 1, wherein the plate pairs of the firsttype and the plate pairs of the second type are sealingly connected toeach other at outer rims of the inlet openings and the outlet openings.12. The plate-and-shell heat exchanger according to claim 1, wherein theplate-and-shell heat exchanger is connected to an electrolyzer such thata fluid feed to a cathode of the electrolyzer, a fluid feed to an anodeof the electrolyzer, as well as a common heating or cooling fluid passesthrough the plate-and-shell heat exchanger.
 13. The plate-and-shell heatexchanger according to claim 2, wherein each plate pair of the firsttype is further provided with a second inlet opening and a second outletopening, and wherein the second inlet opening and the second outletopening of a given plate pair of the first type are sealed from thefirst inlet opening, the first outlet opening and the cavity defined bythe given plate pair of the first type.
 14. The plate-and-shell heatexchanger according to claim 2, wherein each plate pair of the secondtype is further provided with a first inlet opening and a first outletopening, and wherein the first inlet opening and the first outletopening of a given plate pair of the second type are sealed from thesecond inlet opening, the second outlet opening and the cavity definedby the given plate pair of the second type.
 15. The plate-and-shell heatexchanger according to claim 3, wherein each plate pair of the secondtype is further provided with a first inlet opening and a first outletopening, and wherein the first inlet opening and the first outletopening of a given plate pair of the second type are sealed from thesecond inlet opening, the second outlet opening and the cavity definedby the given plate pair of the second type.
 16. The plate-and-shell heatexchanger according to claim 4, wherein the first inlet opening and thefirst outlet opening are formed in one of the heat transfer plates ofthe plate pair, and the second inlet opening and the second outletopening are formed in the other of the heat transfer plates of the platepair.
 17. The plate-and-shell heat exchanger according to claim 2,wherein the plate pairs of the first type and the plate pairs of thesecond type are identical, and rotated at an angle relative to eachother around a centre axis of the plate pairs.
 18. The plate-and-shellheat exchanger according to claim 3, wherein the plate pairs of thefirst type and the plate pairs of the second type are identical, androtated at an angle relative to each other around a centre axis of theplate pairs.
 19. The plate-and-shell heat exchanger according to claim4, wherein the plate pairs of the first type and the plate pairs of thesecond type are identical, and rotated at an angle relative to eachother around a centre axis of the plate pairs.
 20. The plate-and-shellheat exchanger according to claim 5, wherein the plate pairs of thefirst type and the plate pairs of the second type are identical, androtated at an angle relative to each other around a centre axis of theplate pairs.